Andrew Morris stabbed 21-year-old Henry Stangroom in the heart and lungs on October 17 last year, at the flat they shared in Battersea in London.

Mr Stangroom, whose parents live in Rye Common, Odiham, also sustained a wound to his head, thought to have been caused by a harpoon spear.

Morris, 30, then tried to kill himself, first by slitting his wrists and then by firing a harpoon spear into his chin.

The court had heard how Morris had attacked Mr Stangroom in revenge for for his sister, Michelle Stangroom, breaking up with him.

She had been in a relationship with Morris for three years, but broke up with him when he became violent towards her.

Today a jury at the Old Bailey found Morris guilty of murder, rejecting his claims that he had acted in self-defence.

Detective Chief Inspector Diane Tudway, homicide and major crime command at the Met Police, said: “Andrew Morris killed Henry Stangroom in a brutal attack because he felt rejected and because he could not come to terms with that.

“He has not taken any responsibility for his actions and shown no genuine remorse. He took Henry away from a loving and close family who have continued to show amazing strength and dignity.”

Mr Stangroom, a former pupil at Lord Wandsworth College in Long Sutton, had moved to London to work as a chef at The Criterion restaurant in Piccadilly Circus, London.

In a statement, his family said: “There is not justice for our son and brother, nothing will bring him back. The evidence has proved this was a premeditated murder whilst asleep, by a coward hiding behind diminished responsibility.

“We will never be able to come to terms with the loss of Henry, we will never be able to move on, it’s impossible not to think of the terror he must have felt being woken with a spear gun wound to the head and then faced with a maniac with a knife, he would have been in no position to defend himself.”